Push rod structure

ABSTRACT

A push rod of the type which is used to operably interconnect a valve lifter and a valve operating rocker arm comprising an elongated hollow tube having one or more longitudinally extending corrugations or grooves in the wall thereof to improve the strength of the tube and increase the surface area to promote cooling. The invention also includes a method of making the tube.

51 July 31, E973 United States Patent [1 1 Andrews 2,897,805 8/1959 Ill/90.01 Harry E Andrews Bloomfield Hills, 2,960,080 11/1960 Burnard et l23/90.6l Mich.

E R U T C U R T s D 0: m mm mm an UH Prima Examiner-Al Lawrence Smith 7 P od 11 T l 3] Ass'gnee g gz f Cmpmy Attorney-William H. Griffith et al.

Nov. 1,1971

[22] Filed:

ABSTRACT [21] Appl. No.: 194,636

A push rod of the type which is used to operahly inter- [52] l23/90'61 29/1565 74/587 connect a valve lifter and a valve operating rocker arm [5i] Ill. :01. 1/14 comprising n elongated hollow tube having one or [58] Field of Search............... l23/90.6l, 74/587, more longitudinally extending corrugations or grooves in the wall thereof to improve the strength of the tube and increase the surface area to promote cooling. The invention also includes a method of making the tube.

[56] References Cited UNITED STATES PATENTS Almen 123/9061 2 Claims, 4 Drawing Figures 1. PUSH ROD STRUCTURE SUMMARY OF THE INVENTION One object of this invention is to provide an improved push rod which is longer lasting and less subject to failure than those heretofore used.

Another object is to provide a push rod which is stronger and capable of manufacture from relatively light gage material.

Another object is to provide a push rod constructed to promote cooling.

Another object is to provide a push rod comprising an elongated hollow tube having one or more longitudinally extending corrugations in the wall thereof.

Another object is to provide a push rod in which the corrugations are asymmetrically arranged.

Another object is to provide an improved method of making the elongated corrugated hollow tube used in the push rod structure. I M

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a fragmentary side elevational view with parts in section showing a push rod embodying my invention in use.

FIG. 2 is an enlarged fragmentary sectional view of the push rod.

FIG. 3 is a sectional view taken on the line 3-3 in FIG. 2.

FIG. 4 is similar to FIG. 3 showing a modification of the push rod cross section and showing it in the process of being formed.

Referring now more particularly to the drawing, the numeral designates a push rod made according to my invention operably interconnecting a valve lifter 12 and a valve operating rocker 14. Lifter 12 is raised and lowered by a cam 16 on a cam shaft 18 and the lifter moves in a guide 20 which may be formed in an engine block 22. The rocker 14 is pivotally mounted on a shaft 24 with one arm 26 operably engageable with a valve (not shown) and with the other arm 28 on the opposite side of shaft 24 engaged with the push rod. Rocker 14 may be spring biased in a conventional manner for engagement against the push rod. Arm 28 has a projection 29 with a preferably spherical surface 30 engageable with a cup-shaped end piece 32 at one end of the push rod. Valve lifter 12 is provided with a spherical recess 34 for receiving an end piece 36 at the other end of the push rod.

Push rod 10 is formed of a length of tube 38 which may be of a metal such assteel, and has open ends prior to the time when end pieces 32 and 36 are secured thereto. The tube is initially of uniform circular cross section from end to end but is formed preferably by the method hereinafter more fully described so as to have the elongated axially or longitudinally extending grooves or corrugations 40 which may extend throughout the full length of the tube or terminate short of the tube ends as indicated in FIGS. 1 and 2.

The end piece 32 is preferably cup-shaped or hemispherical in form with inner and outer generally spherical surfaces 42 and 44. Spherical surface 42 is dimensioned to snugly receive projection 29 on rocker arm 28. The cross dimension or diameter of the end piece 32 is greater than that of the circular end of tube 38 to which it is secured in any suitable manner as by resistance welding for example.

End piece 36 is preferably cup-shaped as shown having the generally spherical outer surface 46 dimensioned to fit snugly in recess 34 of the valve lifter 12. The transverse dimension of end piece 36 is greater than that of the circular end of tube 38 to which it is secured as by resistance welding.

The end pieces 32 and 36 have apertures 48 and 50 for the flow of lubrication through the tube 38. Lubricant under pressure in the engine block 22 flows into the valve lifter 12 through engine block passage 52, annular groove 54in the body of the valve lifter l2 and valve lifter port 56 which communicates with the annular groove. The port 56 communicates with internal passage 56 which opens through recess 54 in the top of the valve lifter for communication with the interior of the push rod tube 38 through the aperture 50 in end piece 36. The lubricant which thus enters the push rod under pressure will flow through aperture 48 in the end piece 32 to lubricate the projection 29 on the rocker 14.

The push rod of my invention is considerably stronger by reason of the corrugated cross section imparted by the grooves 40. These grooves as shown in FIG. 3 may for example be uniformly spaced apart 90 from one another in a symmetrical distribution. The number of grooves or corrugations is not critical. In high performance engines such as are used in racing cars, there is a high degree of push rod failure which is largely overcome by the strengthening of the push rod in accordance with my invention. It is also possible, in view of the substantial strengthening of the push rod by the corrugated cross section of tube 38, to employ a tube having a somewhat smaller wall thickness, thereby decreasing the overall weight of the push rod structure.

The corrugated cross section of the tube 38 also results in an increased internal surface area of the tube, promoting cooling of the push rod structure through contact with the engine lubricant.

FIG. 4 illustrates a modified tube 38 which differs from tube 38 only in the cross section of the corrugated section. The grooves or corrugations 40' of tube 38 are non-uniformly spaced apart so as to provide an asymmetrical distribution of corrugations. The tendency of push rods to vibrate and for the vibrations to increase in magnitude in accordance with well-known principles of harmonics is reduced by an asymmetrical distribution of the corrugations.

FIG. 4 also discloses the preferred method of forming the corrugations or grooves in the tube. The tube shown in FIG. 4 is initially of uniform circular cross section throughout its length; that is its circular cross section from end to end is of a uniform radius equal to that of the arcuate sections 60 of the corrugated tube.

The circular tube is sleeved on a mandrel 62 to form the corrugations or grooves. The mandrel is an elongated member of the same or greater length than the tube and of uniform cross section throughout its length as indicated in FIG. 4, having the arcuate cylindrical surface portions 64, 66, 68 and 70 separated by the longitudinally extending grooves 72 which extend from one end of the mandrel to the other. The radius of the surface portions 64-70 of the mandrel are equal to the inside radius of the tube so that when the tube is sleeved on the mandrel the surface portions 64-70 of the mandrel contact the inner surface of the tube. The

mandrel is supported for rotation on its axis as indicated by the arrow.

A reciprocable ram 76 is employed which is an elongated flat member of a length equal to the desired length of the corrugations 40' in the tube. FIG. 4 shows one end of the ram. One side edge of the ram is formed to provide a rounded or blunt nose 78 which extends the full length of the ram. The ram is supported in a radial plane of the mandrel and is reciprocated in the direction of the arrow by any suitable means.

In carrying out my method, the tube 38' is sleeved on the mandrel 62 in the initial condition of the tube in which it is circular from end to end, and the mandrel is rotated in the direction of the arrow to align one of the mandrel grooves 72 with the nose 78 of the ram. The ram is then advanced to the left from the retracted position shown to deform the wall of the tube into the cavity or groove 72 in the mandrel to form a corrugation 40, after which the ram is retracted to its illustrated position and the mandrel turned a further increment of rotation to bring the next groove 72 into register with the nose of the ram for another operation of the ram. All of the corrugations 40 are formed in this manner in the wall of the tube.

It will be understood that the tube 38 in FIG. 3 may be formed by the same method described above in connection with the tube 38' of FIG. 4. Obviously the mandrel required to shape the tube of FIG. 3 to the form shown would require an outside surface contour matching the inside corrugated cross section of the tube. What I claim as my invention is:

l. A push rod for operably interconnecting a valve lifter and a valve operating rocker arm in an internal combustion engine, comprising an elongated hollow tube, and bearing portions at opposite ends of said tube, said bearing portions closing opposite ends of said tube and having apertures to permit the flow of lubricant therethrough, the wall of said tube having a plurality of longitudinally extending corrugations therein in circumferentially spaced relation to one another and extending throughout a major part of the length of said tube, said corrugations being asymmetrically arranged.

2. A push rod for operably interconnecting a valve lifter and a valve operating rocker arm in an internal combustion engine, comprising an elongated hollow tube, and bearing portions at opposite ends of said tube, the wall of said tube having a plurality of longitudinally extending corrugations therein in circumferentially spaced relation to one another and extending throughout a major part of the length of said tube, said corrugations being asymmetrically arranged.

I 1 IO! 

1. A push rod for operably interconnecting a valve lifter and a valve operating rocker arm in an internal combustion engine, comprising an elongated hollow tube, and bearing portions at opposite ends of said tube, said bearing portions closing opposite ends of said tube and having apertures to permit the flow of lubricant therethrough, the wall of said tube having a plurality of longitudinally extending corrugations therein in circumferentially spaced relation to one another and extending throughout a major part of the length of said tube, said corrugations being asymmetrically arranged.
 2. A push rod for operably interconnecting a valve lifter and a valve operating rocker arm in an internal combustion engine, comprising an elongated hollow tube, and bearing portions at opposite ends of said tube, the wall of said tube having a plurality of longitudinally extending corrugations therein in circumferentially spaced relation to one another and extending throughout a major part of the length of said tube, said corrugations being asymmetrically arranged. 